Dresden 2011 – scientific programme
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MA: Fachverband Magnetismus
MA 23: Magnetic Shape Memory Alloys I (jointly with MM)
MA 23.1: Talk
Tuesday, March 15, 2011, 12:15–12:30, HSZ 04
Relationship between orientation and strain of polycrystalline Ni50Mn29Ga21 samples — •Claudia Hürrich1, Martin Pötschke1, Stefan Roth1, Bernd Rellinghaus1, and Ludwig Schultz2 — 1IFW Dresden, Institute for Metallic Materials, P. O. Box 270116, 01069 Dresden, Germany — 2Dresden University of Technology, Department of Mechanical Engineering, Institute for Materials Science, 01062 Dresden, Germany
The Ni-Mn-Ga magnetic shape memory alloy provokes plenty of interest for application because of the effect that twin variants reorient by the action of an external magnetic field. Most of the experiments were concentrated on single crystals. But, this effect can also be realised in polycrystals which can be prepared much more efficiently. Here, polycrystalline samples were prepared by directional solidification with a <100> fibre texture of the high temperature cubic phase parallel to the heat flow. A heat treatment was applied for chemical homogenisation and stress relaxation. Samples were heated up to the austenitic state and cooled down under load. The microstructure was analysed by EBSD before and after that treatment. Stress-strain curves were measured at room temperature and at 40°C. As a result of such treatment the twinning stress is reduced and the twinning strain is maximised. This work is supported by DFG within SPP 1239.